| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a highly stable VCO output constantly through simple arrangement and control regardless of variation in characteristics or temperature of the VCO circuit. <P>SOLUTION: The phase locked oscillator has a PLL loop consisting of a phase comparator, a low-pass filter, a main control section, a VCO circuit being driven with a control voltage outputted from the main control section, and a variable frequency divider for dividing the frequency of that output. The control section locks the PLL loop with a plurality of frequencies and measures the control voltage at each locking time, determines a modulation sensitivity of the VCO circuit subjected to linearity calibration based on each control voltage thus measured, and under a state where the PLL loop is opened after being locked with a predetermined frequency, creates a control voltage for generating a frequency variation subjected to linearity correction centering on the predetermined frequency in the VCO circuit based on the modulation sensitivity thus obtained. <P>COPYRIGHT: (C)2008,JPO&INPIT |
